U.S. patent application number 11/726208 was filed with the patent office on 2008-09-25 for thermosiphon boiler plate.
Invention is credited to Mohinder Singh Bhatti, Shrikant Mukund Joshi, Ilya Reyzin.
Application Number | 20080230210 11/726208 |
Document ID | / |
Family ID | 39773545 |
Filed Date | 2008-09-25 |
United States Patent
Application |
20080230210 |
Kind Code |
A1 |
Bhatti; Mohinder Singh ; et
al. |
September 25, 2008 |
Thermosiphon boiler plate
Abstract
A thermosiphon boiler plate assembly (20) for dissipating heat
generated by an electronic device includes a plurality of widthwise
ribs (38) disposed on a top surface (26) of a base (24) extending
parallel to a latitudinal axis (A.sub.x) of the base (24) in spaced
relationship to each other. A plurality of lengthwise ribs (40) are
disposed on the top surface (26) of the base (24) extending
parallel to a longitudinal axis (A.sub.y) of the base (24) in
spaced relationship to each other. The lengthwise ribs (40)
intersect the widthwise ribs (38) on the top surface (26) of the
base (24) to define a plurality of pockets (42) completely
surrounded by the lengthwise and widthwise ribs (40, 38) to
increase the widthwise and lengthwise area moments of inertia
(I.sub.x, I.sub.y) of the assembly (20).
Inventors: |
Bhatti; Mohinder Singh;
(Amherst, NY) ; Reyzin; Ilya; (Williamsville,
NY) ; Joshi; Shrikant Mukund; (Williamsville,
NY) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202, PO BOX 5052
TROY
MI
48007
US
|
Family ID: |
39773545 |
Appl. No.: |
11/726208 |
Filed: |
March 21, 2007 |
Current U.S.
Class: |
165/104.33 ;
165/185; 165/906; 257/E23.088; 361/700 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 23/427 20130101; H01L 2924/0002 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
165/104.33 ;
165/185; 165/906; 361/700 |
International
Class: |
H01L 23/34 20060101
H01L023/34; H05K 7/20 20060101 H05K007/20 |
Claims
1. A thermosiphon boiler plate assembly for dissipating heat
generated by an electronic device comprising; a base having a top
surface and a bottom surface for absorbing heat generated by the
electronic device, a plurality of widthwise ribs disposed on said
top surface of said base, a plurality of lengthwise ribs disposed
on said top surface of said base, and said lengthwise ribs
intersecting said widthwise ribs on said top surface of said base
to define a plurality of pockets on said top surface completely
surrounded by said lengthwise and widthwise ribs to increase a
widthwise area moment of inertia and a lengthwise area moment of
inertia of said assembly for resisting deflection of said
assembly.
2. An assembly as set forth in claim 1 including a chamber disposed
about said top surface of said base for containing a refrigerant
for liquid-to-vapor transformation.
3. An assembly for dissipating heat as set forth in claim 2 wherein
said base has a periphery about said top and bottom surfaces
defined by a pair of length edges and a pair of width edges
defining a base thickness between said top and bottom surfaces in
the range of 0.5 to 1 millimeters.
4. An assembly as set forth in claim 3 wherein said periphery is
rectangular.
5. An assembly as set forth in claim 4 wherein said length edges
and said width edges are equal in length.
6. An assembly as set forth in claim 3 wherein each of said
widthwise ribs have a first rib height with said first rib height
divided by said base thickness being a first height ratio greater
than 0 and not greater than 4 as a factor in the widthwise area
moment of inertia of said assembly.
7. An assembly as set forth in claim 6 wherein each of said
lengthwise ribs have a second rib height with said second rib
height divided by said base thickness being a second height ratio
greater than 0 and not greater than 4 as a factor in the widthwise
area moment of inertia of said assembly.
8. An assembly as set forth in claim 7 wherein said second rib
height is equal to said first rib height.
9. An assembly as set forth in claim 3 wherein each of said
widthwise ribs have a first rib thickness with said first rib
thickness divided by said base thickness being a first thickness
ratio in the range of 1 to 2 as a factor in the widthwise area
moment of inertia of said assembly.
10. An assembly as set forth in claim 9 wherein each of said
lengthwise ribs have a second rib thickness with said second rib
thickness divided by said base thickness being a second thickness
ratio in the range of 1 to 2 as a factor in the widthwise area
moment of inertia of said assembly.
11. An assembly as set forth in claim 10 wherein said second rib
thickness is equal to said first rib thickness.
12. An assembly as set forth in claim 3 wherein each of said
widthwise ribs are spaced from adjacent widthwise ribs a widthwise
distance.
13. An assembly as set forth in claim 12 wherein said widthwise
distance divided by said base thickness is a first distance ratio
in the range of 1 to 6 as a factor in a widthwise elastic constant
of said assembly.
14. An assembly as set forth in claim 13 wherein each of said
lengthwise ribs are spaced from adjacent lengthwise ribs a
lengthwise distance.
15. An assembly as set forth in claim 14 wherein said lengthwise
distance divided by said base thickness is a second distance ratio
in the range of 1 to 6 as a factor in a lengthwise elastic constant
of said assembly.
16. An assembly as set forth in claim 15 wherein said lengthwise
distance is equal to said widthwise distance.
17. An assembly as set forth in claim 3 wherein said base has a
latitudinal axis extending along said top surface equidistant from
said width edges and perpendicular to said length edges with said
widthwise ribs extending parallel to said latitudinal axis in
spaced relationship to each other between said length edges.
18. An assembly as set forth in claim 17 wherein one of said
widthwise ribs extends axially along said latitudinal axis.
19. An assembly as set forth in claim 18 wherein each of said
widthwise ribs are spaced from adjacent widthwise ribs a widthwise
distance.
20. An assembly as set forth in claim 19 wherein each of said
widthwise ribs first adjacent each of said width edges are spaced
said widthwise distance from said adjacent width edges.
21. An assembly as set forth in claim 19 wherein said base has a
longitudinal axis extending along said top surface equidistant from
said length edges and perpendicular to said width edged and
perpendicular to said latitudinal axis with said lengthwise ribs
extending parallel to said longitudinal axis in spaced relationship
to each other between said width edges.
22. An assembly as set forth in claim 21 wherein one of said
lengthwise ribs extends axially along said longitudinal axis.
23. An assembly as set forth in claim 22 wherein each of said
lengthwise ribs are spaced from adjacent lengthwise ribs a
lengthwise distance.
24. An assembly as set forth in claim 23 wherein each of said
lengthwise ribs first adjacent each of said length edges are spaced
said lengthwise distance from said adjacent length edges.
25. An assembly as set forth in claim 23 wherein said lengthwise
distance is equal to said widthwise distance.
26. An assembly as set forth in claim 25 wherein said widthwise
ribs have a rib cross-section defining a first rib height and a
first rib thickness and said lengthwise ribs have a rib
cross-section defining a second rib height and a second rib
thickness with said second rib thickness being equal to said first
rib thickness.
27. An assembly as set forth in claim 26 wherein said first rib
height is equal to said second rib height.
28. A thermosiphon boiler plate assembly for dissipating heat
generated by an electronic device comprising; a base having a top
surface and a bottom surface for absorbing heat generated by the
electronic device and a rectangular periphery thereabout, said
periphery defined by a pair of length edges and a pair of width
edges defining a base thickness between said top and bottom
surfaces in the range of 0.5 to 1 millimeters, said length edges
and said width edges being equal in length, a chamber disposed
about said top surface of said base for containing a refrigerant
for liquid-to-vapor transformation, said base having a latitudinal
axis extending along said top surface equidistant from said width
edges and perpendicular to said length edges, said base having a
longitudinal axis extending along said top surface equidistant from
said length edges and perpendicular to said width edges and
perpendicular to said latitudinal axis, a plurality of widthwise
ribs disposed on said top surface of said base, said widthwise ribs
extending parallel to said latitudinal axis in spaced relationship
to each other between said length edges, one of said widthwise ribs
extending axially along said latitudinal axis, each of said
widthwise ribs being spaced from adjacent widthwise ribs a
widthwise distance, said widthwise distance divided by said base
thickness being a first distance ratio in the range of 1 to 6 as a
factor in a widthwise elastic constant of said assembly, each of
said widthwise ribs first adjacent each of said width edges being
spaced said widthwise distance from said adjacent width edges, each
of said widthwise ribs having a rib cross-section defining a first
rib height and a first rib thickness, said first rib thickness
divided by said base thickness being a first thickness ratio in the
range of 1 to 2 as a factor in a widthwise area moment of inertia
of said assembly, said first rib height divided by said base
thickness being a first height ratio greater than 0 and not greater
than 4 as a factor in the widthwise area moment of inertia of said
assembly, a plurality of lengthwise ribs disposed on said top
surface of said base intersecting said widthwise ribs to define a
plurality of pockets surrounded by said lengthwise and widthwise
ribs to increase the widthwise area moment of inertia and a
lengthwise area moment of inertia of said assembly for resisting
deflection of said assembly, said lengthwise ribs extending
parallel to said longitudinal axis in spaced relationship to each
other between said width edges, one of said lengthwise ribs
extending axially along said longitudinal axis, each of said
lengthwise ribs being spaced from adjacent lengthwise ribs a
lengthwise distance, each of said lengthwise ribs first adjacent
each of said length edges being spaced said lengthwise distance
from said adjacent length edges, said lengthwise distance divided
by said base thickness being a second distance ratio in the range
of 1 to 6 as a factor in a lengthwise elastic constant of said
assembly, each of said lengthwise ribs having a rib cross-section
defining a second rib height and a second rib thickness, said
second rib thickness divided by said base thickness being a second
thickness ratio in the range of 1 to 2 as a factor in the
lengthwise area moment of inertia of said assembly, said second rib
height divided by said base thickness being a second height ratio
greater than 0 and not greater than 4 as a factor in the lengthwise
area moment of inertia of said assembly, said lengthwise distance
being equal to said widthwise distance, said second rib thickness
being equal to said first rib thickness, and said second rib height
being equal to said first rib height.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The subject invention relates to a thermosiphon boiler plate
assembly for dissipating heat generated by an electronic device,
and more specifically, to a low profile thermosiphon boiler plate
assembly having a high plate strength.
[0003] 2. Description of the Prior Art
[0004] Boiler plates have traditionally been used in electronic
apparatuses to dissipate heat from electrical components. A boiler
plate is a device that attaches directly to an electrical device to
enhance the dissipation of heat therefrom. A boiler plate is
generally designed with a base for contacting an electrical device
and a means for dissipating the heat transferred from the device to
the boiler plate. An example of such a boiler plate is disclosed in
U.S. Pat. No. 6,179,046 to Hwang et al. The Hwang et al. patent
discloses a base having a top surface and a bottom surface and a
plurality of spaced fins disposed on the top surface of the base.
The spaced fins are disposed radially around a circumference of a
circular central portion of the base and extend radially outward
from the circumference of the circular central portion along the
top surface of the base. Heat is transferred from an electrical
device to the base, and the base transfers the heat from the fins
to the exterior environment.
[0005] An additional example of a boiler plate is disclosed in U.S.
Pat. No. 6,140,571 to Kitahara et al. The Kithara et al. patent
discloses a base having a top surface and a bottom surface. The
base has a longitudinal axis extending along the top surface of the
base equidistant from a pair of width edges and a latitudinal axis
extending along the top surface of the base equidistant from a pair
of length edges and perpendicular to said longitudinal axis. A
first partition plate is disposed on the top surface extending
along the longitudinal axis and a second partition plate is
disposed on the top surface extending along the latitudinal axis
intersecting the first partition plate. A fan is disposed above the
top surface of the base to propel air towards the top surface of
the base. The partition plates restrict the path of the propelled
air to the outside of the heat sink to prevent a reduction of the
cooling efficiency by the mutual collision of the cooling air.
[0006] Recent advances in electrical components have led to
decreasing device size and increasing capabilities which has
resulted in an increasing of package densities and heat generation
rate. In recent electronic apparatuses, the increasing package
densities have led to a decreasing package size allowing for a
diminishing amount of space to effectively dissipate heat generated
by the electrical components within the electronic apparatuses. The
available space for dissipating heat has become narrower, and the
heat radiation within electronic apparatuses has become an
increasingly difficult problem.
SUMMARY OF THE INVENTION AND ADVANTAGES
[0007] The present invention provides for a thermosiphon boiler
plate assembly for dissipating heat generated by an electronic
device comprising a base having a top surface and a bottom surface
for absorbing heat generated by the electronic device, a plurality
of widthwise ribs disposed on the top surface of the base, and a
plurality of lengthwise ribs disposed on the top surface of the
base. The lengthwise ribs intersect the widthwise ribs on the top
surface of the base to define a plurality of pockets on the top
surface completely surrounded by the lengthwise and widthwise ribs
to increase the widthwise and lengthwise area moment of inertia of
the assembly for resisting deflection of the assembly.
[0008] The present invention provides a thermosiphon boiler plate
assembly that has a low profile, high heat transfer rate, high
plate strength, and low plate mass.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other advantages of the present invention will be readily
appreciated, as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawing wherein the FIGURE is a perspective
view of a thermosiphon boiler plate assembly.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Referring to the FIGURE, wherein like numerals indicate
corresponding parts throughout the several views, a thermosiphon
boiler plate assembly 20 is generally shown for dissipating heat
generated by an electronic device 22.
[0011] The thermosiphon boiler plate assembly 20 comprises a base
24 generally indicated having a top surface 26 and a bottom surface
28 and a rectangular periphery thereabout. The bottom surface 28
contacts the electronic device 22 to absorb heat generated by the
electronic device 22. The periphery is defined be a pair of length
edges 30 and a pair of width edges 32 extending between the
surfaces 26, 28. In an embodiment of the invention as shown in the
FIGURE, the length edges 30 and the width edges 32 are equal in
length defining the periphery of the base 24 as a square.
[0012] The length edges 30 and the width edges 32 define a base
thickness t.sub.b between the surfaces 26, 28. The base thickness
t.sub.b is proportional to a thermal resistance R of the base 24 as
defined by the equation:
R=t.sub.b/(kA)
where "k" is the thermal conductivity of the material of the base
24 and "A" is the surface area of the base 24. In the preferred
embodiment, the thermal resistance R of the base 24 should be as
low as possible to establish a high heat transfer rate to
effectively dissipate heat. The base thickness t.sub.b is
preferably in the range of 0.5 to 1 millimeters.
[0013] A chamber 34 is disposed about the top surface 26 of the
base 24 for containing a refrigerant 36 for liquid-to-vapor
transformation. Heat generated by the electronic device 22 is
absorbed by the base 24 and transferred to the refrigerant 36
contained within the chamber 34. The refrigerant 36 is evaporated
by the heat and the resultant vapor is later condensed and returned
to the chamber 34.
[0014] As shown in the FIGURE, the base 24 has a latitudinal axis
A.sub.x extending along the top surface 26 equidistant from the
width edges 32 and perpendicular to the length edges 30. The base
24 also has a longitudinal axis A.sub.y extending along the top
surface 26 equidistant from the length edges 30 and perpendicular
to the width edges 32 and perpendicular to the latitudinal axis
A.sub.x.
[0015] A plurality of widthwise ribs 38 are disposed on the top
surface 26 of the base 24 to reinforce the assembly 20. Widthwise
ribs 38 of various densities can be used to match the heat flux
footprint of the heat generating device. The widthwise ribs 38
preferably extend parallel to the latitudinal axis A.sub.x in
spaced relationship to each other between the length edges 30. In
an embodiment as shown in the FIGURE, one of the widthwise ribs 38
extends axially along the latitudinal axis A.sub.x and each of the
widthwise ribs 38 are spaced from adjacent widthwise ribs 38 a
widthwise distance s.sub.y. Each of the widthwise ribs 38 first
adjacent each of the width edges 32 are spaced the widthwise
distance s.sub.y from the adjacent width edges 32 as shown in the
FIGURE. The widthwise distance s.sub.y can be varied to vary a
widthwise elastic constant D.sub.x of the assembly 20. The
widthwise elastic constant D.sub.x of the assembly 20 is defined by
the equation:
D.sub.x=E/(12(1-v.sup.2))*EI.sub.y/s.sub.y
where "E" is Young's modulus, "v" is Poisson's ratio, and "I.sub.Y"
is a lengthwise area moment inertia of the assembly 20 expressed
as:
I.sub.y=t.sub.2(h.sub.2+t.sub.B/2).sup.3/12
where "t.sub.2" is a second rib thickness and "h.sub.2" is a second
rib height. The widthwise distance s.sub.y divided by the base
thickness t.sub.b is a first distance ratio preferably in the range
of 1 to 6 as a factor in the widthwise elastic constant D.sub.x of
the assembly 20. The significance of the widthwise elastic constant
D.sub.x is that it is an elastic parameter which determines the
deflection of the assembly 20 along the latitudinal axis A.sub.x.
The greater the value of the widthwise elastic constant D.sub.x,
the greater the resistance of the assembly 20 to deflection along
the latitudinal axis A.sub.x. The deflection of the assembly 20
along the latitudinal axis A.sub.x is inversely proportional to the
widthwise elastic constant D.sub.x.
[0016] Each of the widthwise ribs 38 have a rib cross-section
defining a first rib height h.sub.1 and a first rib thickness
t.sub.1. The first rib height h.sub.1 and the first rib thickness
t.sub.1 can be varied to vary a widthwise area moment of inertia
I.sub.x of the assembly 20. The widthwise area moment of inertia
I.sub.x of the assembly 20 is defined by the equation:
I.sub.x=t.sub.1(h.sub.1+t.sub.b/2).sup.3/12
and the first rib thickness t.sub.1 divided by the base thickness
t.sub.b is a first thickness ratio in the range of 1 to 2 as a
factor in the widthwise area moment of inertia I.sub.x of the
assembly 20. The first rib height h.sub.1 divided by the base
thickness t.sub.b is a first height ratio greater than 0 and not
greater than 4 as a factor in the widthwise area moment of inertia
I.sub.x of the assembly 20.
[0017] A plurality of lengthwise ribs 40 are disposed on the top
surface 26 of the base 24 intersecting the widthwise ribs 38 on the
top surface 26 of the base 24 to define a plurality of pockets 42
on the top surface 26 completely surrounded by the lengthwise and
widthwise ribs 40, 38 to reinforce the assembly 20. The plurality
of pockets 42 defined by the intersection of the lengthwise and
widthwise ribs 40, 38 are completely surrounded on all sides as
shown in the FIGURE. Lengthwise ribs 40 having various densities
can be used to match the heat flux footprint of the heat generating
device.
[0018] The lengthwise ribs 40 preferably extend parallel to the
longitudinal axis A.sub.y in spaced relationship to each other
between the width edges 32. In an embodiment as shown in the
FIGURE, one of the lengthwise ribs 40 extends axially along the
longitudinal axis A.sub.y and each of the lengthwise ribs 40 are
spaced from adjacent lengthwise ribs 40 a lengthwise distance
s.sub.x. Each of the lengthwise ribs 40 first adjacent each of the
length edges 30 are spaced the lengthwise distance s.sub.x from the
adjacent length edges 30 as shown in the FIGURE. In an embodiment
as shown in the FIGURE, the lengthwise distance s.sub.x is equal to
the widthwise distance s.sub.y defining each pocket 42 as being a
square. The lengthwise distance s.sub.x can be varied to vary a
lengthwise elastic constant D.sub.y of the assembly 20. The
lengthwise elastic constant D.sub.y of the assembly 20 is defined
by the equation:
D.sub.y=E/(12(1-v.sup.2))+EI.sub.x/(s.sub.xt.sub.b.sup.3)
where "E" is Young's modulus and "v" is Poisson's ratio. The
lengthwise distance s.sub.x divided by the base thickness t.sub.b
is a second distance ratio preferably in the range of 1 to 6 as a
factor in the lengthwise elastic constant D.sub.y of the assembly
20. The significance of the lengthwise elastic constant D.sub.y is
that it is an elastic parameter which determines the deflection of
the assembly 20 along the longitudinal axis A.sub.y in that the
lengthwise elastic constant D.sub.y is inversely proportional to
the deflection of the assembly 20 along the longitudinal axis
A.sub.y. The deflection of the assembly 20 is inversely
proportional to the square root of the widthwise elastic constant
D.sub.x times the lengthwise elastic constant D.sub.y.
[0019] Each of the lengthwise ribs 40 have a rib cross-section
defining the second rib height h.sub.2 and the second rib thickness
t.sub.2. In the embodiment shown in the FIGURE, the second rib
height h.sub.2 is equal to the first rib height h.sub.1 and the
second rib thickness t.sub.2 is equal to the first rib thickness
t.sub.1. In alternative embodiments, the second rib height h.sub.2
and the second rib thickness t.sub.2 can be varied to vary the
lengthwise area moment of inertia I.sub.y of the assembly 20. The
lengthwise area moment of inertia I.sub.y of the assembly 20 is
defined by the equation:
I.sub.y=t.sub.2(h.sub.2+t.sub.B/2).sup.3/12.
The second rib thickness t.sub.2 divided by the base thickness
t.sub.b is a second thickness ratio in the range of 1 to 2 as a
factor in the lengthwise area moment of inertia I.sub.y of the
assembly 20. The second rib height h.sub.2 divided by the base
thickness t.sub.b is a second height ratio greater than 0 and not
greater than 4 as a factor in the lengthwise area moment of inertia
I.sub.y of the assembly 20.
[0020] While the invention has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *